Yeh sounds like a defective copy of The Secret Ray to me there Jock!
I love my Secret Ray, it's a great edition with a nice page introduction and original artwork from it's serialisation. Looks like you have a bad print, my Rayon title page is full color copy from Le Petit Vingtieme.
It was published in 1994 in the UK
I don't think the race was the reason rather than it's limited appeal, plenty of racism in the more modern tintin books. Interestingly (i found this out at greenwich) the reason why Tintin books stopped containing so much racism was because US publishers didn't like the idea of white people working alongside Black people (hence crews on ships are almost exclusively white)
Here's a link to Jocko's Jungle, not finished but the info under the BOOKS section is all there
http://members.lycos.co.uk/jockosjungle/
Quite a lot of info on all five books, mostly that i've researched myself.
Let me know what you all think
Rik